Peninsula where river boat is, starts to the north (6)
I believe the answer is:
iberia
'peninsula' is the definition.
(Iberia is an example)
'river boat is starts to the north' is the wordplay.
'river' becomes 'aire' (I've seen this before**).
'starts' suggests taking the first letters.
'to the north' is a reversal indicator.
The first letters of 'boat is' is 'bi'.
'aire'+'bi'='airebi'
'airebi' backwards is 'IBERIA'.
'where' acts as a link.
(Other definitions for iberia that I've seen before include "West European peninsula" , "Peninsula encompasing Spain and Protugal" , "old part of Europe" , "European countries" , "Spain and Portugal - airline" .)